use vuetify , v-text-filed, when use :value replace v-model

When <v-text-field></v-text-field> use :value = "somevalue" (initial , somevalue = 1), @change = "FN" (FN (Val) {+ + Val}); If input 1 is equal to the initial value, the page will not change(I think the page should change to 2 because (++1) ); If you enter 2, the page will change to 3 , why? but use v-model no this question, It's like ":value" will remember the last value, which causes the view not to be updated